1. Field of the Invention
The present invention relates to a stabilizer and a leaf suspension using the same.
2. Discussion of Background
There are various suspensions for hanging axles from chassis frames. Among them, a leaf suspension with layered leaf springs has been widely used for vehicles such as trucks since it is of simple structure, less expensive, superior in strength and highly durable.
FIG. 1 shows an example of such leaf suspension in which reference numerals 1 denote a pair of opposite, side rails which extend longitudinally of a vehicle and form parts of a chassis frame; 2, two-layered leaf springs extending along the side rails 1; and 3, an axle in the form of an I-beam connected, through U-shaped bolts 4, to lower surfaces of longitudinally intermediate portions of the leaf springs 2.
A front end of the leaf spring 2 is upwardly wound into an eye 5 which is rockably wound around a horizontal pin 7 on a front bracket 6 of the side rail 1.
A rear end of the leaf spring 2 is upwardly wound into an eye 8 which is rockably wound around a horizontal pin 11 on a shackle 10 of a rear bracket 9 of the side rail 1. Thus, longitudinal expansion and contraction of the leaf springs 2 due to bow-shaped bending of the same are absorbed by rocking the shackles 10.
It is, however, an undeniable fact that such conventional leaf suspension is inferior in riding comfortability of a vehicle to the other existing air suspensions. Therefore, a proposal has been made to improve riding comfortability by interposing air springs 12 between the side rails 1 and upper surfaces of the longitudinally intermediate portions of the leaf springs 12 as shown in FIG. 2.
As to the leaf suspension, inventions of the inventor have been filed, for example, in Japanese Patent Application No. 2002-74857.
In the example shown, brackets 13 are also secured to the portions of the leaf springs 2 where the axle 3 is carried. Rockably fitted to front ends of the brackets 13 are opposite ends 14b of a stabilizer bar 14 which is U-shaped when seeing from above. A laterally extending portion 14a of the stabilizer bar 14 is connected on its two points to a cross member (not shown) between the side rails 1 (see FIG. 1) through a pair of vertically extending stabilizer links 15.
This kind of stabilizer structure itself is well-known in the art. When laterally opposite wheels of the vehicle are concurrently vertically moved, the stabilizer bar 14 is merely laterally uniformly rocked; however, when the wheels are differently vertically moved in the case of, for example, cornering, torsion moment acts on the stabilizer bar 14 and a reaction force thereto causes the wheels to return to their original positions, which is called anti-rolling effect.
In FIG. 2, reference numeral 16 denote mount rubbers for the stabilizer links 15; and 17, brake drums over which the wheels (not shown) are fitted.
In the case of the above-mentioned air leaf suspension using both the leaf springs 2 and the air springs 12, in order to improve the riding comfortability of the vehicle to an extent competitive to those of the existing expensive air suspensions, a pair of leaf springs made of high-strength steel with toughness and with extremely reduced thickness are to be provided so as to attain low rate of spring constant while the air springs 12 are to be larger-sized to give added weight to effectiveness of the air springs 12; however, such improvement in riding comfortability is also accompanied with lowered lateral rigidity of the suspension, resulting in a new problem that rolling of the chassis tends to occur.
More specifically, the lowered lateral rigidity of the suspension causes the chassis to be readily laterally displaced when a centrifugal force acts on the chassis at a side away from the turned side of the chassis at cornering, which increases deviation of the center of gravity of the chassis, resulting in the chassis being readily rolled.
The present invention was made in view of the above and has its object to provide a stabilizer which has swift effectiveness unobtainable in the prior art and affords anti-rolling force instantly in response to any lateral displacement of the chassis and to realize an air leaf suspension using this stabilizer and with lightness in weight, cheapness and improved riding comfortability.